Not Applicable
This invention pertains to information storage technology. More particularly, this invention pertains to tape drives.
The rapid technological developments in computer hardware, and communications, and the proliferation of computers, has led to ever increasing demands for data storage capacity. Presently, there are a variety of information storage technologies suited for different purposes. For example hard drives are the mediums of choice for long term storage of programs and files in personal computers, whereas optical discs that can be written to are coming to supplant 3.5xe2x80x3 magnetic disks for temporary portable file storage.
For portable, high capacity, inexpensive storage, the medium of choice is, at present, magnetic tape. One type of magnetic tape system uses a tape cartridge that houses a single spool on which the magnetic tape is wound. In this single spool type cartridge, there is a lead block that is attached to a free end of the tape (i.e. the outer end). When the tape is fully contained within the cartridge, the lead block is located at an opening in the cartridge through which the tape is withdrawn in use. In order to thread the tape in a tape drive, the lead block is engaged by a pin of a tape threading mechanism that pulls the tape by the lead block through a tape pathway in the tape drive. An example of this type of system is the 3590 tape drive made by International Business Machines, the assignee of the present invention. As the lead block is pulled through the tape pathway, its orientation is in part determined by the tension of the tape to which it is attached. The tension in the tape can vary from one cartridge to another. The location of the lead block is determined by the threading mechanism. Friction in the tape threading mechanism, which varies appreciably from one unit to another due to manufacturing tolerances can effect the speed with which the lead block is pulled through the tape pathway. The speed effects the tension in the tape. If the tension is insufficient, the orientation of the lead block is liable to vary from the intended orientation. A read/write head is located along the tape pathway. Faults in the threading mechanism or insufficient tension in the tape due to the condition of the cartridge, can allow the lead block to assume an orientation in which it will interfere with, i.e. strike, the read/write head. Faults in the threading mechanism can also lead to the pin striking the read/write head.
Striking of the read/write head can damage it, however of greater concern, is the possibility that striking the read/write head will create a nick or burr in the read/write head that will damage any tape subsequently processed by the tape drive. A nick or burr in the read/write head has the potential to cause the destruction of large amounts of data.
What is needed is a system for detecting mechanical fault conditions in a tape drive.
What is needed is a system for detecting mechanical faults in a tape threading mechanism of a tape drive that cause tape lead blocks or parts of the mechanism to strike a read/write head in the tape drive.
The invention provides software and a method for operating a tape drive. In particular, the invention provides methods and software for detecting mechanical faults in a tape drive that includes a read/write head, an actuator for setting a position of the read/write head, and independent position sensor for sensing the position of the read/write head and a servo loop for driving the actuator based on an output of the independent position sensor. Broadly stated, the method comprising the steps of reading an output of the independent position sensor at at least one predetermined time in order to obtain at least on independent position reading and comparing the at least one independent position reading to at least one bound. If the position reading is found to have violated the bound once or found to violate the bound with a certain relative frequency a mechanical fault in the tape drive is inferred, and error message to that effect is output.